INT or 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyl-2H-tetrazolium is a popularly used tetrazolium salt (usually chloride), similar to tetrazolium chloride that on reduction produces a red formazan dye that can be used for quantitative redox assays.
I 1349 (OTTO) Iodonitrotetrazolium chloride, for cell culture, 98%+ Cas 146-68-9 - used for dehydrogenase determination.